The present invention relates to an information processing technology. To be more specific, the present invention relates to an external storage device, and to a method, program and information processing apparatus that are used for processing data stored in an external storage device.
In recent years, with technological advancements such as miniaturization and improved mass productivity of memory devices, external storage devices for personal computers, digital multifunctional machines and other information processing apparatuses have become easily available. Those external storage devices include an external storage device provided with a USB (Universal Serial Bus) terminal as a data input/output interface (such a device is hereinafter also referred to simply as a “USB memory”).
With an external storage device, a user of the external storage device can easily transport data between plural information processing apparatuses by moving data, such as files, into the external storage device from an information processing apparatus having a data input/output interface, and then by retrieving the data on another information processing apparatus.
However, the facilitating of data transport by use of external storage devices has in turn been increasing security concerns over information leakage and other problems. For this reason, companies in the related industry have been conducting research and development on techniques for solving security problems accompanying the spread of external storage devices.
As a background technique related to the above problems, Japanese Patent Application Publication No. 2006-146744 discloses a removable medium information management system configured as below. The removable medium information management system previously set a content validity period in an offline environment for content stored in a removable medium, the set content validity period being different from and shorter than the original validity period of the content. The removable medium information management system updates and extends the content validity period in an offline environment when the removable medium is once used on a PC having been connected to and authenticated by an authentication.
As another background technique, Japanese Patent Application Publication No. 2007-66288 discloses a data processing apparatus capable of preventing use of data in a storage medium which has expired. The data processing apparatus acquires an expiration date and time of digital data stored in a removable medium having been made usable, and acquires current date and time information. Then, the data processing apparatus determines, by comparing the acquired current date and time with the acquired expiration date and time, whether or not the digital data has expired. If determining that the digital data has expired, the data processing apparatus warns that the data having expired is stored in the removable medium.
As another background technique, Japanese Patent Application Publication No. 2007-249575 discloses an information processing apparatus including connection monitoring means which monitors whether a transportable recording medium is connected to the information processing apparatus, and security check activation means. In the transportable recording medium, there are recorded: target information to be used in processing; apparatus identification information unique to every information processing apparatus which uses the target information; and a security check program which functions as use judgment means for judging whether or not an information processing apparatus has a right to use the target information by use of the apparatus identification information, and as use control means for performing control so that the information processing apparatus can use the target information if the use judgment means judges that the information processing apparatus has the right, and whose execution is limited. The security check activation means activates the use judgment means included in the security check program when the connection monitoring means detects the connection of the transportable recording.
As another background technique, Japanese Patent Application Publication No. 2007-257616 discloses a recording medium being attachable to and detachable from plural host apparatuses, and having digital data recorded therein. The recording medium includes: judgment means that judges whether or not the digital data is usable; and deletion means that deletes the digital data if the digital data is judged as being unusable. The recording medium records therein information indicating a validity period of the digital data. By using the information, the judgment means judges whether or not the digital data has expired. The deletion means deletes the digital data if the digital data is judged to have.
As another background technique, Japanese Patent Application Publication No. 2008-140127 discloses a secondary storage device for a computer. The secondary storage device is attachable to and detachable from a computer and which includes information storage means that stores, in the secondary storage device, information to be read by the computer or information written by the computer. The device includes: validity period storage means that retains information on a validity period of stored information, which is set upon attachment of the device to the computer or upon saving of the stored information after the attachment of the device; and validity period management means that, when the device is attached again to the computer after being detached therefrom, prior to enabling the computer to read the stored information, deletes or inhibits reading of the stored information if the validity period of the stored information stored in the validity period storage means is over.
The user of an external storage device may in some cases need to use different validity periods respectively for apparatuses to each of which the external storage device is connected in order to perform security control over data stored in the external storage device. For example, the user may need to prevent a thief of the external storage device from accessing data in the device as reliably as possible in such away as to: set a longer validity period of data for a personal computer used for storing the data in the external storage device for the first time (which is most likely to be one owned by the user himself or herself); and set a shorter validity period thereof for an apparatus other than the above personal computer. However, the above need is not met by any of prior techniques including the above-described Patent Literatures.
One of objectives of the present invention is to provide an improved external storage device, method, program and information processing apparatus that are advantageous in enhancing security of data stored in the external storage device used for information processing apparatuses.
Another one of the objectives of the present invention is to provide an improved external storage device, method, program and information processing apparatus that are advantageous in setting, for data stored in the external storage device to be connected by information processing apparatuses, different validity periods respectively for the information processing apparatuses.
Still another one of the objectives of the present invention is to provide an improved external storage device, method, program and information processing apparatus that are advantageous in enhancing security of data stored in the external storage device to be connected by information processing apparatuses, by use of different validity periods set respectively for the information processing apparatuses.